[packagekit] Slight spawned backend API change

[Richard Hughes]

I've merged into master a tiny change, where the boolean values that
get sent from the daemon (as text) now appear to the python class as
True and False, rather than "true" and "false", and the enabled value
from RepoDetail is now a boolean, not a string. This fixes a bug I've
wanted to fix for a while where the backends have to deal with strings
for boolean values. A few backends already treat these values as
boolean and not string, which shows me that it's already a problem.

This affects apt, conary, pisi, portage, smart and yum.

I think I've fixed up all the affected backends with this change
(9502099c003d6bdba0ab95584c3f5fdc39b6c912), but please test your
backend and ensure it still works correctly.

Thanks,

Richard.